20mm in tire difference was noticeable for me. 245 to a 265. Steering was heavier but some vagueness was added. Fuel mileage also decreased.
I think the more important thing is better or grippier tires vs. just going wider. I think for most applications, sans heavy track use, just a better tire would benefit most vs. trying to slap the largest tire on possible.
I know the GD fenders are not as wide as the GR but I couldn't imagine a 17x9 causing problems if you keep the offset within reason and the tire size sane. When you think about it, the wheel is one inch wider but really only a half inch wider each side of the centerline
However the GD is not where my experience is and this would be better discussed in the appropriate thread.